title: Copper/zinc superoxide dismutase from the Cladoceran Daphnia magna: molecular cloning and expression in response to different acute environmental stressors.
abstract: The copper/zinc superoxide dismutase (Cu/Zn-SOD) is a representative antioxidant enzyme that is responsible for the conversion of superoxide to oxygen and hydrogen peroxide in aerobic organisms. Cu/Zn-SOD mRNAs have been cloned from many species and employed as useful biomarkers of oxidative stresses. In the present study, we cloned Cu/Zn-SOD cDNA from the cladoceran Daphnia magna, analyzed its catalytic properties, and investigated mRNA expression patterns after exposure to known oxidative stressors. The full-length Cu/Zn-SOD of the D. magna (Dm-Cu/Zn-SOD) sequence consisted of 703 bp nucleotides, encoding 178 amino acids, showing well-conserved domains that were required for metal binding and several common characteristics. The deduced amino acid sequence of Dm-Cu/Zn-SOD showed that it shared high identity with Daphnia pulex (88%), Alvinella pompejana (56%), and Cristaria plicata (56%). The phylogenetic analysis indicated that Dm-Cu/Zn-SOD was highly homologous to D. pulex. The variation of Dm-Cu/Zn-SOD mRNA expression was quantified by real-time PCR, and the results indicated that the expression was up-regulated after 48-h exposure to copper, un-ionized ammonia, and low dissolved oxygen. This study shows that the Dm-Cu/Zn-SOD mRNA could be successfully employed as a biomarker of oxidative stress, which is a common mode of toxicity for many other aquatic hazardous materials.
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University , 1 Wenyuan Road, Nanjing 210023, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Lyu
authors.forename: Xuexia
authors.initials: X
authors.lastname: Zhu
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Wang
authors.forename: Yafen
authors.initials: Y
authors.lastname: Chen
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D003621:Daphnia / Q000201:enzymology*; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D013482:Superoxide Dismutase